1. Field of the Invention
This invention relates generally to an image pickup device, such as a digital camera, and an image pickup method capable of adjusting the view angles, and more particularly to an image pickup device and an image pickup method for automatically adjusting the view angles relative to a target subject.
2. Description of Related Art
With the developments in various digital technologies, an image pickup device such as a digital camera and a digital camcorder are becoming widely common at the present day. Capturing high-definition images has become possible with the increase in the number of pixels for solid state image sensors such as CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor) sensors. Moreover, an image pickup device having an optical zoom lens with an automatic focus function also is becoming common, which makes it possible for people not accustomed to using a camera to easily change the view angles by setting the zoom magnification ratio from a wide angle to a telescopic angle and easily capture an image that is in-focus.
However, setting a visual outline or a composition for taking a picture is difficult particularly for a beginner, and there are times when captured images are not composed in a way intended by the photographer, such as that a target subject may be too large or too small, or unrelated background may be captured more widely than the target subject.
A prior solution is disclosed for example in Japanese Laid-Open No. 6-22263, which discloses an image capturing method in which images having wide, telescopic, and intermediate view angles are captured at the same time by automatically capturing an image of a subject in multiple zoom magnification ratios in addition to the zoom magnification ratio set at the time of photography, allowing the photographer to select an image with an appropriate angle of view after the photo-shooting.
Japanese Laid-Open No. 2004-109247 discloses a method in which an image is captured by changing the zoom magnification ratio toward a wider angle than that being set at the time of photography, and from this wider-angle image, an image having the captured range intended by the photographer and an image with the same zoom magnification ratio and having a captured range displaced from the intended captured range are generated, so that the photographer can select an image in an appropriate captured range.
Japanese Laid-Open No. 2005-117316 discloses a method where particularly a person is set as a photographic target, and the position and orientation of the camera is controlled by a moving mechanism so that feature portions of the person's face detected by a detection means for detecting the feature points of the person's face such as the eyes, the ears and the nose are positioned in a reference region within the frame, thereby controlling the position and size of the face to be photographed.
However, the method disclosed in Japanese Laid-Open No. 6-22263 photographs a target subject only by changing the zoom magnification ratios and it does not consider the position of the target subject within the field of view of the image. Therefore, there is a possibility that the automatically photographed images may include a target subject disproportionately positioned at the lower side of the image or a target subject may be cut at a margin of the image.
In the method disclosed in Japanese Laid-Open No. 2004-109247, the obtained image will have inferior resolution if a conventional solid state image sensor is used without modification because the image is being cropped and enlarged to its original dimensions. On the other hand, to maintain the fineness of the image, a larger solid state image sensor needs to be used which necessitates an increase in the size of the image pickup device.
The method disclosed in Japanese Laid-Open No. 2005-117316 uses a camera which is fixed at a single site and has a large-scale moving mechanism for controlling the position and orientation of the camera with many motors such as a rotary motor and a tilt motor, and thus, it is not suited for a portable device.